Nowadays, printed circuit board (PCB) is widely used in various fields to allow electronic components mounted thereon to connect to other assemblies so as to accomplish the predetermined objectives. Normally, the PCB is composed of an insulation substrate and wirings specially designed in accordance with different requirements and embedded therein so as to allow electronic components mounted on the insulation substrate thereafter to electrically connect to other assemblies via the connection of the wirings. Before the formation of the wirings, a layer of copper foil is provided on top of the insulation substrate. Then a removal process, such as an etching process, is applied to the copper foil to remove unnecessary part of the copper foil. What is left on the surface of the insulation substrate becomes a mesh-like wiring. This mesh-like wiring is called conducting wiring or layout to provide electrical connection for the electronic components mounted on the insulation substrate.
Some sort of the substrates is made of aluminum or iron and the wiring is formed on the surface of the aluminum or iron substrate. This type of printed circuit board is largely used in the engine bay of automobiles. And it is a well known phenomenon that the longer the engine keeps running, the higher temperature the engine bay becomes. Under such severe working conditions, some passive electronic components welded on the substrate may therefore fall off from the substrate due to the effect of the heat so generated by the working of the engine as well as that so generated by the working of the passive electronic components.